The **FORCES** range enables clear and comprehensive learning of **STATICS** and **DYNAMICS** covering a variety of theories and topics. An understanding of the way in which forces act and react, is fundamental when studying the application of loads on a variety of fixed structures and rotating machinery. The **FORCES** form a comprehensive range of equipment, from fixed beams through to rotating machines apparatus, equally suitable for demonstration and experimental work.

The moment of inertia of a rolling object is the rotary analogy of mass and governs the rotary acceleration. It can be determined in three ways; by rolling, oscillation or direct calculation. All should ideally give the same result but the student can be introduced to differences caused by different experimental techniques.

This apparatus teaches students about the confluence of the four forces at the end of the wall jib crane and clearly illustrates the application of a triangle of forces. This wall mounted self-contained jib crane has spring balances built into its two members. After loading the member lengths can be adjusted to their no-load lengths. The experiment allows the student to determine the experimental values of the forces in the principal parts of the jib crane, study the effect of altering the length of the tie to change the geometry and to compare the results with the forces obtained from graphical solutions using a polygon or a triangle of forces. The jib out-hangs and the crane cable inclination can be readily changed. A set of calibrated weights and load hangers are supplied.

The apparatus consists of a jib restrained by two chain ties making a triangulated three dimensional structure. The jib and both ties are fitted with spring balances so that the internal forces can be measured.

The basic roof truss consists of two rafters or struts and a restraining tie. Both rafters are pivoted at their apex.

The other end of one of the rafters is pivoted to a free standing base, whilst the remaining rafter end runs on ball bearings along a track.

This apparatus is designed to evaluate forces within a toggle mechanism. Load is applied to the two pairs of links by a hanger suspended from their connecting pivot. One end of the link is pivoted to the base, while the other end is able to move sideways on low friction ball bearing wheels. The moving links are restrained by a horizontal spring balance, which measures the horizontal reaction directly. The angle of the toggle can be varied and adjustment is provided for returning the geometry to its original unloaded state before taking measurements. There are many ways in which the forces can be determined theoretically. The instruction sheet provided with the apparatus takes the opportunity to introduce the use of velocity diagrams to solve essentially static problems by considering virtual motion.